Vacuum-ture radiotransmitter



3 1 May 927 e. MESSTORFF VACUUM TUBE RADIOTRANSMITTER Filed Nov. 25. 1923 N VE/VTOR GERHARD MESSTORFF.

'A TTURNE Y.

Patented -May 3, 1927.

UNITED stares 63m nnss'ronrr, or srannau, man. nnnnm, GERMANY, ASSIGNOB 'ro rm 7 1mm: nn. E3103 2. Hum a m. 3.111., or nnnnm, on:

VAGUUHPTUBE RADIOTBAHSMITTEB.

Application filed November 28, 1923,8erla1 No. 676,562, and in Germany April 28, 19%.

For the transmission of wireless telephony tube transmitters are generally used for the modulation of a constant transmitting wave for the purpose of superimposing in a sim- 5 ple manner the speech oscillations over the carrier oscillations.

It is desirable to employ such transmitters for ordinary telephone conversations without switching over from talking to receiving,

for which several methods are known.

' This present invention has for its object to provide a simple method of modulation and to reduce the consumption of energy of the transmitter between the intervals of speech.

My invention will be more clearly understood from the specification hereinafter following by reference to the accompanying drawing which diagrammatically illustrates the application of my invention to an electron tube transmitter circuit.

In the circuit arrangement of my invention a choking-coil with iron core with direct current magnetism is inserted in the grid-circuit or antenna or feed back circuit of the transmitter, the magnetizing current of such coil being varied in well known method by the speech currents.- According to my invention a resistance is inserted into the magnetism circuit, oneterminalof which 7 is connected with the filament, the other, terminal with the grid of the oscillator tube. Between the terminal of this resistance with the grid the alternating current winding of the choking coil is inserted. By the drop of.

tension at the resistance the grid has normal- 1y a negative potential impressed thereon of such value that the tube cannot oscillate which, if necessary, maybe controlled by a.

9 special additional source of direct current. When speech commences, the. current in the resistance increases, the grid becomes more positive, whereby the transmitter may start to oscillate, while simultaneously the modulation of the carrier waves isefi'ected by 1 operation of the circuit including the chok ing coil 3. Between the'intervals of'speech the transmitter does not and it 18 possible withoutcompensatory circuit to transmit and receive with the mine antenna. Alchoking circuit, blocking the transmitting waves may be inserted in thev receiver c1rcnit' in a well known way, I have illus- .trated the branch resistance as migustable so that it may be adjusted in such way that the transmitter operates at maximum amplitude at the loudest vocals. The drawing illustrates the details of circuit wherein reference character 1 designates the oscillator tube, which is excited to generate oscillations by the circuit as shown on the drawing, numeral 4 designates the antenna circuit, numeral 3 denotes the grid circuit of the oscillator in which the choke coil.

system 5 having an iron core is inserted, the direct current winding of which is desig-' nated 6. For the purpose of keeping the alternating current from the direct current winding 61 provide small choke coils 17 in circuit with the direct current winding 6. The branch resistance is shown at 7 arranged to regulate automatically the existing source of tension 16 in the grid circuit in accordance with this invention. Reference char- I acter 2 designates themodulation tube. the

plate current of which effects the ni'agnetizing of the chokin coil system 5 as well as the potential of e existing source 16 connected with the grid. Numeral Sdesignates aftransformer, the primary winding of which is controlled by a suitable microphone circuit 10. In case of tele phy it is sufficient to key the grid-circuit of tube 2 by a suitable make and break device actuated in accordance with signals.

It will be understood that the iron core choke coil 5 is' constituted by two windings 11 and 12 formed on separate core members 14 and 15. The direct current winding 6 is wound upon one leg of each of the core members 14 and 15. Windings 11 and 12 are positioned on opposite sides of the winding 6 and are connected in entirely separate electrical circuits. Windings 11 and 12 are connected in series and disposed in the gridcircuit 3of the oscillator 1 Winding 6 is coli- I nected in the output circuit of modulator tube 2.-

The arrangement of the potential con; trolling circuit constituted by resistor 7 andbattery 16 is such that operation of the circuits of the modulator tube in accordance with sound vibrations efiects a change in. grid potential at the oscillator 1 at the same time controlling the operation of the input circuit of the oscillator 1. By reason of thissimultaneous control, oscillations may be 7 started and stopped in the antenna circuit and modulated by voice or other signals while intermediate the period of modulation the carrieufrequency .is suppressed.

I have described my invention in a certain preferred embodiment, but I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

Having now particularly described, and

ascertained the natureof my said invention and in what manner. the sameis to be performed I declare that what I claim is:

1. An electron tube transmitter circuit comprising an electron tube arranged to generate high frequency oscillations, an electron tube arranged to modulate theocsillations thus generated, grid, filament and plate electrodes for each of said tubes, input and output circuits interconnecting said electrodes, an iron cored inductively coupled system interlinking the output circuit'of said second mentioned electron tube with the input circuit of said first mentioned electron tube and means in circuit with said second mentioned electron tube for controlling the operating potential of the grid electrode of said first mentioned tube simultaneously with a change in condition of said iron cored inductively coupled system.

2. A high frequency signal transmission system comprising a plurality of electron tubes each having grid, filament and plate electrodes, input and output circuits interconnecting said electrodes, one of said tubes being arranged for the genera 'on of high frequency oscillations and the ther of said tubes being arranged for modulating the oscillationsgenerated by said first mentioned electron tubes, an inductively coupled system interposed between the input circuit of g said first mentioned electron tubeand the output circuit of said second mentioned electron tube, means interposed in series with the output circuit of said second mentioned electron tube and in series with said inductively coupled system for controlling the potential of the grid electrode of said first mentionedelectron tube in accordance with the operation of said second mentioned electron tube while modulation is efiected through said inductively coupled means by variation ,in the magnetic condition of said inductively coupled system.

3, In a high frequency transmission circuit, a plurality of electron tubes each having grid, filament and plate electrodes with input and output circuits interlinking said electrodes, a magnetic coupling system comprising an iron core, a secondary winding disposed onlsaid iron core and connected in the input circuit of one of said tubes, a primary winding disposed on said iron core and connected in the output circuit of another of said tubes, the output circuit of said last mentioned tube including a resistor, connections between saidresistor and the grid electrode of said first mentioned tube, means for controlling the current in the output circuit of said last mentioned tube in accordance with sound vibrations for vari ably controlling the'magnetic condition of said coupling system and varying the potential of the grid electrode of said first mentioned tube whereby oscillations may be started and stopped in the circuits ofsaid first mentioned tube upon actuation of the circuits of said second mentioned tube and said oscillations modulated in accordance with a change in the magnetic condition of said coupling system.

4. A high frequency signal transmission system comprising a plurality of electron tubeseach having grid, filament and plate electrodes, input and output circuits interconnecting said electrodes, an inductively coupled system comprising an iron core, a pair of windings on said core, one of said windings being included in the input c-ir:

cuit of one of said tubes and the other of said windings being included in the output circuit of another of said tubes, a resistor included in the output circuit of said last mentioned tube, a series circuit including said resistor, a source of potential and the rid and filament electrodes of said first mentioned electron tube, said last mentioned electron tube having its circuits controlled by sound vibrations for varying the magnetic condition of said coupled system and controlling the potential of the grid electrode of said second mentioned tube whereby said second mentioned tube may be initiated in a condition of oscillation and said oscillations modulated in accordance with changes in the magnetic condition of said coupled system.

In testimony whereof I afix my signature.

GERD SSTORFF. 

